Rockwell Commander 112 - Air Bleed Nozzles; Flow Divider Valve

SECTION IV
POWER PLANT
AND PROPE~LER
MAINTENANCE MANUAL
ROCKWELL
COMMANDER
112/B/TC /TCA
FUEL
STRAINER
IDLE
ADJUSTING
NEEDLE VALVE
LOCK
PLATE
MODELS 112TC/TCA
X2431A7
Figure 4-6. Carburetor
serve tachometer for any change during leaning pro-
cess. Caution must be observed to return mixture
control lever to FULL RICH position before RPM
drops so low engine cuts out. An increase of more
than 10 RPM while leaning indicates an excessively
rich idle mixture. An immediate decrease in RPM
(if not preceded by a momentary increase) indicates
idle mixture is too lean.
e. If idle adjustment is too rich or too lean, turn
idle mixture adjustment in direction required for cor-
rection, and recheck new setting. Each time an ad-
justment is made, engine should be run up to 2000
RPM to clear engine before making another adjust-
ment. Monitor cylinder head and oil temperature
gages to remain within limits.
f. In the event the setting above does not remain
stable, check the idle linkage; any looseness in the
linkage will cause erratic idling. In all cases, allow-
ance must be made for the effect of weather conditions
and field density altitude during adjustments.
FLOW DIVIDER VALVE
MODELS 112/B. The fuel flow divider valve, located
on the upper center of the engine, consists of a
spring-loaded diaphragm actuated poppet valve'-
Action of the diaphragm is controlled by servo pres-
sure from the servo regulator valve. A spring seats
the fuel flow divider valve needle to retain fuel within
the flow divider valve when the engine is stopped. The
sensitivity obtained from fuel flow divider valve ope-
ration prevents engine rpm lag during rapid throttle
movement and eliminates the need for an acceleration
pump. The fuel flow divider valve directs fuel to each
cylinder through individual lines connected to ports in
the valve. Fuel passes through the air bleed nozzles
4-10
before entering the cylinder. A fuel line is connected
between the fuel flow divider fuel flow port and a fuel
flow
gage, located in the instrument panel, to provide
an accurate indication of metered fuel flow to the
engine.
AIR BLEED NOZZLES
MODELS 112/B. An air bleed nozzle installed in each
cylinder, directs fuel from the flow divider valve
into the cylinder intake port. Each nozzle in-
corporates an air bleed, which aids in vaporizing fuel
at idle rpm by breaking the high vacuum at the intake
manifold, and assures that the fuel lines from the flow
divider valve are full of fuel at all times. The imme-
diate availability of fuel in the fuel lines ensures posi-
tive engine acceleration and eliminates the need for an
engine primer during engine starting. Air bleed
nozzles have an identification number or letter stamped
on one of the flats of the no zzle body hexagon head,
which also indicates that the nozzle air bleed hole is
on the opposite flat. To eliminate fuel leakage at the
air bleed hole after engine shutdown, the nozzle must
be installed with the identification mark facing down-
ward. Fuel nozzles should be removed and changed
when an engine is running rough and exhibits poor
acceleration characteristics, not attributed to faulty
ignition. When this is the case all nozzles on the
appropriate engine should be removed and cleaned.
MODELS 112/B. REMOVAL AND CLEANING. Dis-
connect the fuel inlet line and use a deep socket to
remove the nozzle. Cap the fuel line and plug hole in
cylinder. Clean the air bleed nozzles as follows:
a. Wash in clean unleaded gasoline or cleaning
solvent. Trichlorethylene may be used to clean noz-
zles that show signs of carbon buildup.
b. Apply
filtered compressed air at 100 psi to dis-
charge port of nozzle.
Do not use wire or tools to clean nozzle
orifices.
MODELS 112/B. INSTALLATION. Install air bleed
nozzles in cylinders, so that identification number
or letter is located on the lower side of the nozzles
when tightened into engine cylinder.
[~
When replacing fuel lines and fittings,
use only a fuel soluble lubricant, such
as engine oil on thread fittings. 00
NOT USE ANY FORM OF THREAD
COMPOUND.
Change 1
Copyright Commander Owners Group 2013 All Rights Reserved
**unofficial copy**